Sodium thiocyanate: a probe for the conformations of the androgen-receptor complex

In the presence of sodium thiocyanate (NaCNS), partially purified 5 alpha-dihydrotestosterone-receptor (DHT-R) complexes extracted from normal genital skin fibroblasts (GSF) dissociate with complex (biphasic) kinetics. The rate constant of the 'fast' component and the magnitude of the 'slow' component vary with temperature (29-37 degrees C) and NaCNS concentration (0.1-0.4 M). Equimolar sodium bromide is much less effective; potassium chloride up to 1 M has no effect. DHT-R complexes from the GSF of a subject with partial androgen insensitivity (PAI) yield biphasic dissociation profiles that differ from normal and are influenced by NaCNS. Together with the temperature-dependent, first-order (monophasic) dissociative behavior of normal DHT-R complexes in the absence of NaCNS (Kaufman et al., 1982), the foregoing data have been used to construct a kinetic model involving the dissociation of DHT from 3 conformationally related forms of the androgen-receptor complex: (1) dysactivated; (2) preactivated; (3) activated.